\begin{lem}\label{xyz} 
    \[ \left\{      
        \begin{matrix}
            p \in \al    \\
            q \notin \al 
        \end{matrix}
        \right\} 
        \implies p < q.\]
        \end{lem}

        This text should be at the beginning of the line.

        \begin{lem}\label{xyz} 
            \[ \left\{      
                \begin{matrix}
                    p \in \al    \\
                    q \notin \al 
                \end{matrix}
                \right\} 
                \implies p < q.\]
                \end{lem}
